The present invention relates to a plastic molded product using a resin composition with polypropylene as the main component. More precisely, the present invention relates to a plastic molded product using a resin composition with polypropylene as the main component having a high melt strength and a high crystallization temperature.
Polypropylene is widely used in all molding fields, because its superior mechanical qualities and resistance against chemicals are conveniently combined with high economic efficiency. However, its melt strength and its crystallization temperature are low, so that not only is it of inferior moldability in molding fields such as blow molding, expansion molding and extrusion molding, but also there are limits to the production rate with respect to most other molding methods as well.
To raise the melt strength and the crystallization temperature of polypropylene, methods have been disclosed wherein molten polypropylene reacts with an organic peroxide and a crosslinking agent (see for example Publication of Unexamined Patent Application (Tokkai) No. Sho 59-93711 and Tokkai No. Sho 61-152754), and a method has been disclosed wherein half-crystalline polypropylene reacts in the absence of oxygen with a peroxide having a low dissolution temperature, so that a polypropylene having a free end long chain branching and not comprising gel is produced (Tokkai No. Hei 2-298536).
As another method to improve the dissolving viscoelastic properties such as the melt strength, a composition combining a polyethylene and a polypropylene with differing intrinsic viscosity and molecular weight, and a method for producing such a composition by multistep polymerization, have been proposed.
For example, in Published Examined Patent Application (Tokko) No. Sho 61-28694, a method has been disclosed wherein 2-30 weight parts of ultrahigh molecular weight polypropylene are added to 100 weight parts of regular polypropylene and extrusion molding is performed in a temperature range above the melting point and below 210xc2x0 C. In Tokko No. Hei 1-12770, an extruded sheet with two polypropylene components of different molecular weights and an intrinsic viscosity ratio of at least 2, which is obtained by a multistep polymerization method, has been disclosed. In Tokko No. Sho 62-61057, a method for melt kneading and a method for multistep polymerization of a polyethylene composition consisting of three kinds of polyethylenes with differing viscosity and average molecular weight, comprising 1-10 wt % of a high viscosity, average molecular weight polyethylene have been disclosed. Tokko No. Hei 5-79683 discloses a polymerization method for polyethylene, wherein between 0.05 and 1 wt % of an ultrahigh molecular weight polyethylene having in intrinsic viscosity of not less than 20 dl/g is polymerized by multistep polymerization using a high activity titanium vanadium solid catalyst component. Tokko No. Hei 7-8890 discloses a polymerization method for polyethylene, wherein 0.1-5 wt % of an ultrahigh molecular weight polyethylene having an intrinsic viscosity of not less than 15 dl/g is polymerized by multistep polymerization in specially arranged curing units using a high activity titanium catalyst component preliminarily polymerized with 1-butene and 4-methyl-1-pentene.
In Tokkai No. Hei 5-222122, a method is disclosed for producing polypropylene having high melt strength, by polymerization of propylene using a preliminary polymerization catalyst that results from the preliminary polymerization of ethylene and a polyene compound with a support type solid catalyst comprising titanium and an organic aluminium compound catalyst. Tokkai No. Hei 4-55410 discloses a method for producing ethylene xcex1-olefin copolymer having high melt strength by us ing a preliminary polymerization catalyst comprising ethylene and a polyethylene with an intrinsic viscosity of not less than 20 dl/g, wherein preliminary polymerization is performed exclusively in the ethylene by using the same catalyst as in Tokkai No. Hei 5-222122.
Although it has to be acknowledged that in the various components proposed in the prior art as described above and in the production processes belonging thereto the melt strength has been somewhat increased, many aspects such as a residual odor caused by the crosslinking agent, the crystallization temperature and the heat stability have to be improved.
Moreover, in a multistep polymerization that incorporates a production process of high molecular weight polyolefin into a main polymerization of a regular polypropylene (co)polymerization process, the precise control of the polypropylene (co)polymerization for formation of a small amount of high molecular weight olefin is difficult, and a low polymerization temperature is necessary for formation of the polypropylene with a sufficiently large molecular weight, which lowers the rate of production for the final polypropylene composition. Thus, improvement of the process is necessary.
In the method for preliminarily polymerizing a polyene compound, it is necessary to prepare the polyene compound separately. In the method for preliminarily polymerizing polyethylene, the dispersibility of the preliminarily polymerized ethylene in a finally obtained polyolefin compound is not uniform, so that from the viewpoint of stability of the polyolefin compound, improvement of the process is required.
As has been pointed out above, the problems of low melt strength and low crystallization temperature of polypropylene, as well as the problems of odor and heat stability are inherent in the prior art, so that an improvement of polypropylene plastic molded products is strongly desired.
In order to solve the problems of the prior art, it is a first object of the present invention to provide a plastic molded product using a polypropylene resin composition, which has high melt strength and high crystallization temperature, as a main component.
A second object of the present invention is to provide a resin foam having uniformly fine foaming cells (bubbles) and a high expansion ratio using a polypropylene composition.
A third object of the present invention is to provide a sheet or film plastic using a polypropylene composition having high melt strength and excellent moldability in a thermoforming, vacuum forming, pressure forming and the like.
A fourth object of the present invention is to provide a hollow plastic article using a polypropylene composition with high melt strength and high crystallization temperature, which has excellent moldability with regard to hollow plastic molding, the hollow plastic article having high resistance against drawdown at shock, high production, high stiffness and high stiffness against heat.
A fifth object of the present invention is to provide an injection molded plastic product using a polypropylene composition having high melt strength and high crystallization temperature, which has excellent heat resistance and stiffness.
A sixth object of the present invention is to provide a polypropylene fiber and nonwoven fabric with high melt strength and high crystallization temperature, which has excellent heat resistance and stiffness.
A seventh object of the present invention is to provide a tube-shaped continuous plastic, which does not whiten with impact, has a high impact strength at low temperatures and can be produced with high productivity using high melt strength and high crystallization speed.
In order to achieve the above objects, a plastic molded product of an olefin (co)polymer composition according to the present invention is provided, which comprises:
(a) 0.01-5.0 weight parts of high molecular weight polyethylene, which is an ethylene homopolymer or an ethylene-olefin copolymer containing not less than 50 wt % ethylene units and has an intrinsic viscosity xcex7E in the range of 15-1000 dl/g measured in tetralin at 135xc2x0 C.; and
(b) 100 weight parts of an olefin (co)polymer which consists of a propylene homopolymer or propylene-olefin copolymer containing not less than 50 wt % propylene units and has an intrinsic viscosity xcex7P in the range of 0.2-10 dl/g measured in tetralin at 135xc2x0 C.
In the plastic molded product, it is preferable that the high molecular weight polyethylene exists as finely dispersed particles having a number-average particle size of 1-5000 nm.
In the plastic molded product, it is also preferable that the number-average particle size of the high molecular weight polyethylene is 10-500 nm.
In the plastic molded product, it is also preferable that the intrinsic viscosity xcex7T of the olefin (co)polymer composition measured in tetralin at 135xc2x0 C. is 0.2-10 dl/g.
It is also preferable that the plastic molded product satisfies the equation
log(Gxe2x80x2(xcfx89=100))xe2x88x92log(Gxe2x80x2(xcfx89=10xe2x88x922)) less than 2,
wherein Gxe2x80x2(xcfx89=100) is the storage elastic modulus at a frequency of xcfx89=100, and Gxe2x80x2(xcfx89=10xe2x88x922) is the storage elastic modulus at a frequency of xcfx89=10xe2x88x922 of the molten olefin (co)polymer composition at 230xc2x0 C.
It is also preferable that the plastic molded product satisfies the equation
log(N1) greater than xe2x88x92log(MFR)+5,
wherein N1 is a first normal stress difference at a shear rate of 4xc3x9710xe2x88x921(secxe2x88x92) of the olefin (co)polymer composition at 190xc2x0 C., 230xc2x0 C. and 250xc2x0 C. and MFR is a melt flow rate.
It is also preferable that the plastic molded product satisfies the equation
(N1(190xc2x0 C.)xe2x88x92N1(250xc2x0 C.))/N1(190xc2x0 C.) less than 0.6,
wherein N1(190xc2x0 C.) and N1(250xc2x0 C.) are first normal stress differences at a shear rate of 4xc3x9710xe2x88x921(secxe2x88x921) of the olefin (co)polymer composition at 190xc2x0 C. and 250xc2x0 C. respectively.
It is also preferable that the plastic molded product satisfies the equation
xe2x80x83(MS(190xc2x0 C.)xe2x88x92MS(250xc2x0 C.))/MS(190xc2x0 C.) less than 3.1,
wherein MS(190xc2x0 C.) and MS(250xc2x0 C.) are the melt strengths at a shear rate of 3xc3x9710xe2x88x921(secxe2x88x921) of the olefin (co)polymer composition at 190xc2x0 C. and 250xc2x0 C. respectively.
In the plastic molded product, it is also preferable that the plastic molded product satisfies the equation
(G(t=10)xe2x88x92G(t=300))/G(t=10) less than 1,
wherein G(t=10) is a relaxation elastic modulus with t=10sec and G(t=300) is a relaxation elastic modulus with t=300sec of the molten olefin (co)polymer composition at 230xc2x0 C. under 500% strain.
In the plastic molded product, it is also preferable that the elongational viscosity when the olefin (co)polymer composition is molten and stretched increases in a region where deformation is large, indicating strain hardenability of the olefin (co)polymer composition.
In the plastic molded product, it is also preferable that the high molecular weight polyethylene particles are added before or during olefin (co)polymerization.
It is also preferable that the plastic molded product satisfies the following equation
log(MS) greater than 4.24xc3x97log(xcex7T)xe2x88x921.20,
wherein MS is the melt strength of the olefin (co)polymer composition at 230xc2x0 C. and xcex7T is the intrinsic viscosity measured in tetralin at 135xc2x0 C.
It is also preferable that the plastic molded product satisfies the following equation
log(MS) greater than 4.24xc3x97log(xcex7T)xe2x88x921.05,
wherein MS is the melt strength of the olefin (co)polymer composition at 230xc2x0 C. and xcex7T is the intrinsic viscosity measured in tetralin at 135xc2x0 C.
It is also preferable that the plastic molded product satisfies the following equation
4.24xc3x97log(xcex7T)+0.24 greater than log(MS) greater than 4.24xc3x97log(xcex7T)xe2x88x921.10,
wherein MS is the melt strength of the olefin (co)polymer composition at 230xc2x0 C. and xcex7T is the intrinsic viscosity measured in tetralin at 135xc2x0 C.
In the plastic molded product, it is also preferable that 0.001-2 weight parts of not less than one stabilizer selected from the group consisting of a phenol antioxidant and a phosphorous antioxidant is added to 100 weight parts of the olefin (co)polymer composition.
It is also preferable that the plastic molded product is not less than one plastic selected from the group consisting of a resin foam, a film, a sheet, a laminate covering a substrate surface, a hollow plastic, an extrusion plastic, a fiber, a nonwoven web and a tube-shaped continuous plastic.
It is also preferable that the plastic molded product is a resin foam, and the resin foam is not less than one selected from the group consisting of a container and a sheet.
It is also preferable that the foam sheet is laminated on a metal plate.
It is also preferable that the expansion ratio of the foam is in the range of 1.1-5.0.
It is also preferable that the plastic molded product is a film or a sheet molded by a T-die method satisfying the equation
280xe2x89xa7(PPxe2x88x92T1)xe2x88x92(CHxe2x88x92T2)xe2x89xa7120,
wherein (PP-T1) is a temperature of not less than 180xc2x0 C. but less than 350xc2x0 C. of the molten propylene polymer composition for molding and (CH-T2) is a surface temperature less than 80xc2x0 C. of a chillroll of a molding machine.
It is also preferable that the plastic molded product is a film or a sheet having not less than one of the basic lamination structures selected from the group consisting of [A]/[B], [A]/[B]/[A], and [B]/[A]/[B], wherein the polypropylene composition (x) of claim 1 is used for layer [A], and not less than one polypropylene composition (y) selected from the group consisting of crystalline propylene homopolymer and crystalline propylene-olefin copolymer containing not less than 50 wt % propylene units is used for layer [B].
It is also preferable that the ratio of the total thicknesses of layer [A] and layer [B] is at least in the range [A]:[B] =20:1-1:20.
It is also preferable that the plastic molded product is a film or a sheet, wherein the polypropylene composition film according to claim 1 is laminated onto at least one surface of a polypropylene biaxially stretched film.
It is also preferable that the plastic molded product comprises
{A} 99-90 wt % of the polypropylene composition according to claim 1, which is a propylene polymer or a propylene-olefin copolymer comprising not less than 50 wt % propylene units, has a melt flow rate of 5-100 g/10 min at 230xc2x0 C. and 21.18N and comprises
polypropylene (a) with an intrinsic viscosity xcex7P of 0.2 dl/g-10 dl/g measured in tetralin at 135xc2x0 C., and
0.01-5 weight parts (for 100 weight parts of polypropylene (a)) of polyolefin (b) with an intrinsic viscosity xcex7E of 15 dl/g-100 dllg measured in tetralin at 135xc2x0 C.; and
{B} 1-10 wt % of crystalline or low crystalline ethylene xcex1-olefin copolymer having a melt flow rate of 1-50 g/10 min at 230xc2x0 C. and 21.18N.
It is also preferable that the plastic molded product is a coated plastic.
It is also preferable that the plastic molded product is a hollow plastic article using olefin polymer having a melt flow rate of 0.1-20 g/10 min at 230xc2x0 C. and 21.18N.
It is also preferable that the resin further comprises 5-30 wt % of not less than one substance selected from the group consisting of
(Y1) an ethylene homopolymer with a density of 0.914-0.930 g/cm3 and a melting point (Tm) of 100-118xc2x0 C.,
(Y2) an ethylene-olefin copolymer with a density of 0.920-0.935 g/cm3 and a melting point (Tm) of 115-127xc2x0 C.,
(Y3) an ethylene-olefin copolymer with a density of 0.880-0.920 g/cm3 and a melting point (Tm) of 110-115xc2x0 C.,
(Y4) a crystalline ethylene polymer with a density of 0.935 -0.968 g/cm3 and a melting point (Tm) of 125-136xc2x0 C.,
(Y5) an ethylene-olefin copolymer rubber,
(Y6) an ethylene-olefin nonconjugated diene copolymer rubber
(Y7) an ethylene-vinyl acetate copolymer with a density of 0.92-0.95 g/cm3 and a melting point (Tm) of 90-110xc2x0 C., and
(Y8) an inorganic filler, which is added to 95-70 wt % of the olefin polymer composition according to claim 1.
It is also preferable that the inorganic filler is at least one of the substances selected from the group consisting of talc, calcium carbonate, potassium titanate whiskers, mica and glass fiber.
It is also preferable that the plastic molded product is a multilayer hollow plastic article comprising
an inner layer comprising the olefin polymer composition (X) according to claim 1 having a melt flow rate (230xc2x0 C.; 21.18N) of 0.1-20 g/10 min and consisting of 0.01-5 weight parts of said component (a) and 100 weight parts of said component (b); and
a surface layer comprising a polypropylene composition (W) consisting of 100 weight parts polypropylene with a crystalline melting point of 135xc2x0 C.-165xc2x0 C. and 0.05-1 weight parts nucleating agent.
It is also preferable that the olefin polymer composition according to claim 1 accounts for 95-70 wt % of the inner layer and further comprises 5-30 wt % of not less than one substance selected from the group consisting of
(Y1) an ethylene homopolymer with a density of 0.914-0.930 g/cm3 and a melting point (Tm) of 100-118xc2x0 C.,
(Y2) an ethylene-olefin copolymer with a density of 0.920-0.935 g/cm3 and a melting point (Tm) of 115-127xc2x0 C.,
(Y3) an ethylene-olefin copolymer with a density of 0.880-0.920 g/cm3 and a melting point (Tm) of 110-115xc2x0 C.,
(Y4) a crystalline ethylene polymer with a density of 0.935-0.968 g/cm3 and a melting point (Tm) of 125-136xc2x0 C.,
(Y5) an ethylene-olefin copolymer rubber,
(Y6) an ethylene-olefin nonconjugated diene copolymer rubber
(Y7) an ethylene-vinyl acetate copolymer with a density of 0.92-0.95 g/cm3 and a melting point (Tm) of 90-110xc2x0 C., and
(Y8) an inorganic filler.
It is also preferable that the plastic molded product is a fiber having the above-mentioned plastic molded product according to claim 1 as one fiber component; and not less than one thermoplastic resin selected from the group consisting of a thermoplastic polyolefin resin and a thermoplastic polyester resin as another component; the fiber is formed as a regular fiber of one of the above components, a conjugated fiber of both components or a mixed fiber made of both components, the polypropylene composition accounts for 100-50 wt %, and the average fiber diameter is preferably 0.1-10 xcexcm.
It is also preferable that the plastic molded product is a fiber and a fiber component according to claim 1 is used as a sheath component and a crystalline polypropylene is used as a core component, and the conjugation ratio (sheath component/core component) is in the range 20/80-60/40 (wt %).
It is also preferable that in the plastic molded product, the fiber is formed into a nonwoven fabric web.
It is also preferable that the fibers constituting a nonwoven fabric web are made only of the polypropylene composition according to claim 1.
It is also preferable that the fibers constituting a nonwoven fabric web are conjugated fibers comprising the polypropylene composition according to claim 1 and not less than one thermoplastic resin selected from the group consisting of polyolefin thermoplastic resin and polyester thermoplastic resin, and the polypropylene composition accounts for not less than 50 wt %.
It is also preferable that the fibers constituting a nonwoven fabric web are mixed fibers comprising the polypropylene composition above-mentioned and regular fibers or conjugated fibers of not less than one thermoplastic resin selected from the group consisting of polyolefin thermoplastic resin and polyester thermoplastic resin, and the polypropylene composition accounts for not less than 50 wt %.
It is also preferable that the plastic molded product further comprises 0.10-10 wt % hydrogenated styrene elastomer for 99.9-90 wt % of the polypropylene composition according to claim 1.
It is also preferable that the hydrogenated styrene elastomer has a melt flow rate (SR-MFR) (230xc2x0 C.; 21.18N) of 0.5 g/10 min-10 g/min.
It is also preferable that the hydrogenated styrene elastomer has a styrene concentration of not more than 30 wt %.
It is also preferable that the hydrogenated styrene elastomer is a hydrogenated ethylene-butene-styrene elastomer.
It is also preferable that the plastic molded product is a continuous tube-shaped plastic.
It is also preferable that the continuous tube-shaped plastic is obtained by melt extruding a polyolefin resin composition into a metal mold in vacuum condition and molding it into a tube shape.
It is also preferable that the plastic molded product is a continuous tube-shaped plastic obtained by melt extruding a polyolefin resin composition with a melt flow rate (PP-MFR) (230xc2x0 C.; 21.18N) of 0.1 g/10 min-10 g/10 min into a metal mold in vacuum condition and molding it into a tube shape.